<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script src="https://unpkg.com/vue@next"></script>
<div id="app" >
    <div :style="{fontSize: curSize + 'em'}">
        <blog-item v-for="blog in blogs" :title="blog.title" :key="blog.id"
                   @showbig="curSize+=$event"></blog-item>
    </div>

</div>
<script>
    const vueOpt = {
        data() {
            return {
                blogs: [{title: 'aaa', id: 1}, {title: 'bbb', id: 2}],
                curSize: 1
            }
        }
    }

    const app = Vue.createApp(vueOpt)
    app.component('blog-item', {
        data() {
            return {}
        },
        props: ['title'],
        emits: ['showbig'],
        template: `
            <span>{{title}}</span>
            <button @click="$emit('showbig', 0.1)">click Me</button>
        `
    })
    app.mount('#app');

</script>
</body>
</html>
